1. Field of the Invention
The instant invention relates to an electrical plug and a mating electrical female or socket connector clamp for maintaining engagement between such plug and such socket connector, and more specifically, to such a clamp for accomplishing this without forcibly gripping or damaging the electrical cords associated with either.
2. The Prior Art
A portable electrical appliance such as a power saw, vacuum cleaner or the like is often used with an extension cord connected to the electrical cord of the appliance. The connected cords sometimes snag on obstructions during movement of the appliance and pull apart the connection between the plug of the appliance and the female or socket connector of the extension cord. Sometimes the plug and socket connector only partially separate, dangerously exposing portions of the plug contacts.
Various contrivances have been proposed for clamping together such a plug and female connector to prevent their inadvertent separation. These include the devices described in U.S. Pat. Nos. 2,753,536 (Tjader); 3,609,638 (Dany); 3,999,828 (Howell); and 4,221,449 (Shugart, Jr.), none of which satisfactorily prevents electrical connectors from being pulled apart.
The device described by Howell employs a friction clamp to frictionally grip the cord of a fitting, to retain the fitting in mating contact with a second fitting. However, such a friction clamp does not work reliably when the cord is wet or oily. Moreover, if such a clamp is used repeatedly on the same cord, the cord insulation is eventually damaged by the abrading action of the clamp.
The device described by Dany is adjustable only after removal from the cords being clamped. Further, it is characterized by protrusions that can snag on foreign objects, especially if the joined cords are dragged over rough ground.
The Shugart device is retained in position by the engagement under tension of a locking member having serrations. The Tjader device employs a spring clamp. Both devices are subject to abrupt disengagement if subjected to vibration or a sudden pull on the cords.
The Carmo device, U.S. Pat. No. 4,664,463 issued May 12, 1987 and assigned to the assignee of the instant invention, went a long way to eliminate the various problems noted above with respect to the prior art devices. It did, however, lack the ability to rapidly install or remove the clamping means from the electrical cord and the ability to rapidly remove or install the clamping means in the overall clamp. Normally the cord 16 would be fed through clamping means 30 and then the connector 14 could be installed to the cord 16 end or if the connector was molded with the cord, then the appliance could be installed at the free end of cord 16.
It is suggested at Column 5, line 12 et seq that clamping means 30 could be cut or slit along with end abutment boss 36 as shown at 58 of FIG. 1 so that connector 14 and cord 16 could be installed into clamping means 30 and boss 36 or removed therefrom. The limited flexibility of the clamp material is relied upon to prevent unwanted withdrawal of cord 16 and connector 30 but this limited flexibility must be relied on if the cord 16 and connector 14 are to be placed in the clamp. A very unsatisfactory approach. If the flexibility is low enough to retain cord 16 and connector 14, it will most likely be very difficult to get connector 14 and cord 16 into the clamp unless wedges are used, making the clamp very difficult to use.
The '463 patent described a plug and female connector clamp which securely maintains a plug and female or socket connector in mating contact without any necessity for forcibly gripping their cords. The clamp does not damage the insulation of the cords with repeated use and is not susceptible to failure under vibration, or as a result of sudden pulls on the plug and female connector cords. Further, its configuration reduces any tendency for it to snag on foreign objects.
The clamp comprises an elongated housing having spaced apart sides and end abutments defining a central space for receiving an engaged plug and female connector. The cords extending from the plug and female connector pass through openings in the end abutments. The cord 18 to plug 12 passes through deflecting arms 34 to a cord opening 32 making it relatively simple to install or remove cord 18.
However, it is difficult to install or remove cord 16 from clamping means 30 and boss 36. The cord 16 would have to be string through the clamping means 30 and boss 36 while at lease one end was unterminated, which makes it difficult to use a clamp of this type where it was not intended from the start to use such a clamp to ameliorate this problem the clamping means 30 and boss 36 could be cut open so that the cord 16 could be removed from the boss 36 and clamping means 30 without severing the end connectors of cord 16. The limited flexibility of the material of clamping means 30 and boss 36 is relied on both to allow removal and installation of cord 16.